Life in the Universe
Written by Gerry Barrow   
Before we discuss the possibility of life elsewhere in the universe, we should first define what is meant by life, and see how it may have arisen here on earth. Until recently, death was defined as the moment at which the heart stops beating. With the advent of heart transplants and respirators, a new definition, based on alpha and delta waves of the brain, was introduced. One day, brain transplants may render even this definition obsolete. When a person dies, the body’s biochemistry does not immediately change to something that is incompatible with life. The fact that ‘dead’ people can be resuscitated is proof of this. However if we were to artificially combine all the organic compounds that make up a living organism, in the correct quantity and form, the result would not automatically come to life.

Life may be looked upon as a flow of energy through an organism. However, even this broad definition is hardly adequate. A car may come to ‘life’ when its ignition is turned on, but even the most expensive Mercedes cannot reproduce itself. The most advanced super computer, capable of 100 million calculations per second, is too dumb to produce one original thought. The humble donkey can do both with its eyes closed.

In the 1920s, a soviet biochemist, A.I. Oparin suggested that life may have come from non living matter under conditions that existed on the primitive earth. Experiments were performed in which an electric spark ignited a mixture of nitrogen, methane ammonia, water vapour and hydrogen. This was meant to simulate the effects of lightning and ultra-violet radiation on the primordial atmosphere. The experiment resulted in the creation of amino acids, the building blocks of proteins. Since all life forms on Earth are made of proteins, the experiment was seen as proof of a possible non-divine creation of life. The presence of amino acids on meteorites has also been quoted as evidence of the existence of life elsewhere in the universe. How amino acids joined together to form proteins, and the proteins became self-replicating living matter  remains to be demonstrated. The genetic code found in all organisms on earth would suggest that life appeared only once, and that all the diverse forms of plants and animals evolved from this primitive creation.

Before the advent of scientific thought, any occurrence that could not be readily explained was attributed to some divine being. Every religion has its own vague explanation for the creation of the world. If the current theory for the birth of the universe is accepted, God’s role comes within a nano-second of being redundant. As a Biochemist, however, His tenure is secure. The complex interactions of enzymes, hormones and tissue needed to sustain life cannot easily be explained by evolution and natural selection. The theory of divine intervention will have to suffice until something better comes along.

Mars is considered the most likely place in the solar system where evidence of extraterrestrial life may be found. About 4 billion years ago, when the planet was warmer, water is believed to have penetrated fractures in the subsurface rock, possibly forming an underground water system. The water was saturated with atmospheric carbon dioxide, and carbonate minerals were deposited in the fractures. It is believed that living organisms may have assisted in the formation of the carbonate, and some remains of the microscopic organisms may have become fossilized. 15 million years ago, a huge comet or asteroid struck Mars, ejecting a piece of rock from its subsurface location with enough force to escape the planet. For millions of years the chunk of rock floated through space. It encountered the Earth’s atmosphere 13,000 years ago and fell in Antarctica as a meteorite. In tiny globs of carbonate researchers have found a number of features that suggest past life. These include organic molecules and microscopic fossil structures strikingly similar to bacteria found on Earth.

The two Viking missions to Mars in 1976 addressed three questions: (1). The nature of organic material, if any, on the surface; (2) The possible presence of objects on the surface whose appearance or motion would suggest living or fossilized organisms; and (3) The possible presence in Martian soil of agents that could indicate metabolic processes. The investigations showed no trace of any complex organic material or evidence of biological activity. These results are considered inconclusive because of the small area sampled. Europa, one of the major Jovian satellites, was shown by Voyager I in 1979 to be covered by smooth cracked ice. Tidal heating by Jupiter might heat the icy material enough to maintain a subsurface ocean of liquid water. Water vapour in its atmosphere breaks down to form trace amounts of oxygen,  not enough to support life. The surface temperature of –145 degrees Celsius is incompatible with life as we know it.

What about the rest of the universe? With as many galaxies as there are stars in our own, the universe is a very big place. Our milky way is about 1010 years old and contains 2 x 1011 stars, with about 10 new stars being born every year. Gravitational perturbations in the proper motions of stars indicate the presence of dark companions in half the number of nearby stars. Recent observations, in which the light from the star was obscured, have shown disc-like structures which are thought to be planetary systems. U.S Astrophysicist F.D.Drake, devised a method for determining the probability of extraterrestrial intelligence in our galaxy based on the product of the following parameters: (a) The average rate of star formation over the lifetime of the galaxy; (b) the fraction of stars with planetary systems; (c) the number of planets per star suitable for the origin of life; (d) the fraction of planets on which life in fact arises; (e) the fraction of such planets on which intelligent life evolves;  (f) the fraction of such planets on which a technical civilization develops; (g) the mean lifetime of a technical civilization. The result of these computations predict the presence of intelligent life only a few hundred light years from earth.

What would these ‘space people’ look like? Not like us, that’s for sure. Carbon is the only element capable of forming the long chains that make up most organic molecules. With carbon, oxygen and water abundant in the universe, there is no shortage of raw materials for the creation of life as we know it. Silicon can also catenate to some extent, so we must also consider the possibility of non-hydrocarbon based life-forms. Creatures made of quartz may be better adapted for life in an alien environment. When one considers the huge diversity of plants and animals right here on Earth, it is a safe bet that extra terrestrial life-forms will be stranger than we can imagine.

Are there aliens among us? Are ancient artifacts, such as the Nasca drawings of Peru, proof of extraterrestrial contacts? I hardly think so. While, from a statistical point of view, the chances are in favour of life elsewhere in the universe, I don’t believe that aliens in UFOs visit us with any regularity. The universe is too large, and we too insignificant to make Earth a popular  holiday destination. Also, given the age of the universe, and our relatively short time here, the chances of any living person observing such a visit is absolutely zero. Technology advances exponentially, so that other life in the universe would be either very primitive or far more advanced than us. For us to visit them is out of the question due to the vast distances involved. Until another Einstein comes along and revamps the laws of Physics, all we can do is wait and watch. SETI, the search extraterrestrial intelligence in the universe, uses radio telescopes to seek out and analyze signals from space. The 305m instrument of Arecibo Observatory is powerful enough to receive signals transmitted by a comparable telescope located 1000 light years away. This means that radio communications with technical civilizations on nearby planetary systems is feasible. So far, nothing beyond the background echoes of space has been detected. We should not despair and give up, the search has only just begun. With this universe, anything is possible.

 
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